This invention relates to a lathe provided with a number of working tools for making a setting in metallic objects such as jewels, rings, bracelets and the like, the size of the setting being directly determined by taking the diameter of the gem to be set.
More particularly, a machine according to the invention is characterized by the fact that at least one of the tools is provided with a system which causes the tool for working or the setting to shift on to be adjusted in accordance with the size or dimension of the gem. More specifically, the shifting or adjusting may be applied to both a first traditional tool for the rough grinding or cutting and a second tool for further more precise grinding or cutting of the setting. In accordance with the invention, there are provided three other tools of the riveting type which, by deforming the metallic material, effect the definitive setting and the subsequent finishing work.
In accordance with the invention, the position of at least the first two working tools is varied with respect to the axis of the hole or opening of the setting by means of a mechanical system capable of intented detecting the dimensions of the gem to be set. More particularly, the axial shifting of the tool with respect to the axis of the setting takes place according to a predetermined reduction scale, allowing for the fact that the size to be taken corresponds to the diameter of the gem, while the shifting of tool affects the setting radius.